1. Field of the Invention
The present invention relates generally to an endoscope, particularly to a curved part provided to an insertion part of an endoscope.
2. Description of Related Art
A base end of an insertion part of an endoscope is connected with a manual control part. A curved part is formed at the other end of the insertion part. The curved part is constructed by connecting a plurality of joint rings in the axial direction of the insertion part. Each joint ring comprises an annular main body and a connecting part, which is projected from the end of the main body. The main bodies of the joint rings are connected with each other at regular intervals by connecting the adjacent connecting parts of the joint rings. Curve control wires are inserted to the inside of the joint rings for controlling the curved part. On the inner periphery of the joint rings, a plurality of pins (guide members) are projected, and the curve control wires are inserted into guide holes formed at the ends of the pins.
Japanese Patent No. 2843370 discloses a curved part of an endoscope in which the pins are rotatably inserted in the inner periphery of the joint rings, and stoppers are formed at base ends, which are positioned at the outside of the joint rings, of the pins. The pins are prevented from falling into the inside of the joint rings by contact of the stoppers to the outer periphery of the joint rings; moreover the pins are also prevented from falling to the outside of the joint rings by inserting the curve control wires into the guide holes of the ends of the pins. With this construction, however, when the insertion part of the endoscope is assembled, the pins must be held from the outside during inserting the curve control wires into the guide holes of the pins in order to prevent the pins from falling to the outside of the joint rings; thus attaching the curve control wires causes some difficulties.
Many internal members, such as a light guide and a forceps tube, are arranged inside the insertion part of the endoscope. Then, as the curved part is controlled, the internal members touch with the projected part, such as the pins, and the internal members are damaged due to the large stress applied to them. The light guide, especially, is made of a bundle of glass fibers, and thus it is easily broken. In consideration of the problem mentioned above, Japanese Patent Application Laid-open No. 9-294710 discloses an endoscope in which the internal members are protected by covering them with resin tubes, cylindrical coil bodies, net tubes, and the like. However with this construction, an outer diameter of the curved part is made large because of the covering members, thus a filling rate of the curved part becomes adversely high. As the filling rate of the curved part becomes high, the internal members cannot smoothly move within the curved part because the internal members and the joint rings, or the internal members themselves interfere with each other, and the control of the curved part is adversely affected. Hence, the conventional endoscope needs a thicker curved part in order to reduce the filling rate.
The curved part is provided with a spare amount of angle so that the curved part can be curved by larger angles than it is required. For example, the curved part that requires 180 degrees of curving angle is constructed to be able to curve by approximately 210 degrees provided approximately 30 degrees of spare amount. However, with the construction of the conventional curved part of the endoscope, as the curved part is controlled, the curved part curves from the base end side, and the spare amount concentrates on the tip component side of the curved part; hence the tip component side cannot curve sufficiently. Then, a substantial length of the tip component, which is formed at the tip of the insertion part of the endoscope, becomes long and because of that the tip component cannot make small turns. A view area from a viewing window provided to the tip component is small and narrow as a result.
In view of the above-described circumstances, the present invention has as its object the provision of a curved part of an endoscope with curve control wires that can be inserted easily through guide holes of guide members.
Another object of the present invention is to provide a curved part of an endoscope that does not damage internal members of an insertion part of the endoscope, while an outer diameter of the insertion part can be narrowed.
Still another object of the present invention is to provide a curved part of an endoscope that can make a viewing area from a viewing window larger by sufficiently curving a tip component side of the curved part.
In order to achieve the above-described object, the present invention is directed to a curved part of an insertion part of an endoscope, comprising: a plurality of joint rings which are connected with each other along an axial direction of the insertion part; a plurality of guide members, each of the plurality of guide members being rotatably attached to an inner periphery of each of the plurality of joint rings, each of the plurality of guide members having a guide hole, each of the plurality of guide members having, on an outer periphery thereof, a first stopper preventing the guide member from falling into an inside of the joint ring and a second stopper preventing the guide member from falling to an outside of the joint ring; and a curve control wire which curves the curved part, the curve control wire being inserted in the guide holes of the plurality of guide members.
Accordingly to the present invention, the first and second stoppers are formed on the outer periphery of the body of the guide member; thus the guide member does not fall to either the inside or the outside of joint rings. Thus, the guide member does not have to be held when the curve control wire is inserted into the guide hole of the guide member, so that the curve control wire can be easily attached.
Preferably, a protection member is attached to the guide member or a projection formed at the inner periphery of the joint ring so as to protect an internal member provided in the curved part of the endoscope.
According to the present invention, since the protection member is attached to the projection, the internal member is not damaged even if the internal member touches the projection. Further, a filling rate of the insertion part of the endoscope is not large like in the case in which the internal member is covered with a protection member; thus, the insertion part of the endoscope can be narrowed.
In order to achieve the above-described object, the present invention is directed to a curved part of an insertion part of an endoscope, comprising: a plurality of joint rings which are connected with each other along an axial direction of the insertion part such that intervals between bodies of the adjacent joint rings become larger toward an tip component side of the curved part than a base end side of the curved part.
According to the present invention, the intervals between the bodies of the adjacent joint rings are larger at the tip component side than the base end side of the curved part; thus the tip component side is more easily curved than the base end side. Thereby, as controlling the curved part of the present invention, both the base end side and the tip component side are sufficiently curved so that the substantial length of the tip component is short. Thus, the tip component can make small turns, and hence a viewing area of a viewing window provided to the tip component is large.